Abstract
Various experimental tools have been applied for the characterization of materials and evaluation of their functionalities. Among them, thermodynamic methods are unique in the sense that the energetic and entropic aspects inherent in materials can be directly observed. Physical quantities obtained from thermodynamic measurements reflect macroscopic aspects of materials. However, because those quantities are closely related to the microscopic energy schemes of all kinds of molecular degrees of freedom in a statistical manner, one can gain detailed knowledge on the microscopic level on the basis of precise thermodynamic investigations. Among them, heat capacity calorimetry is an extremely useful tool to investigate thermal properties of materials, in particular at low temperatures. For correct understanding of functionality of materials, it is crucially important to complementarily adopt both spectroscopic and/or structural methods leading to microscopic aspects of materials and thermodynamic methods revealing energetic aspects. The aim of this thematic issue is to review calorimetric studies on functional inorganic materials to show the important roles played by thermodynamic studies. The topics picked up in Part II of this thematic issue are the following six functional materials: [1] Mixed-valence metal complexes M(II)M(III)X (M = Pt, Ni) and [2] Mixed-valence metal complex Fe(II)Fe(III)(dto)3: Electron transfer between the mixed-valence metal ions provide a variety of phase transitions in which the magnetic and electronic properties are dramatically altered [3]. Assembled bimetallic complex: By changing the bimetallic ions, various dimensional assemblies are established. Some complexes exhibit dimensional crossover by temperature change. Dramatic changes in the magnetic and/or electronic properties are sensitively reflected on thermodynamic quantities [4]. Organic conductor (DMe-DCNQ)2Cu and [5] Organic super conductors: The charge transfer complexes consisting of organic molecules and inorganic counter ions give various metallic compounds. The electron correlations and electron-phonon coupling occuring in them produce a variety of phase transitions such as metal-insulator, magnetic, and superconductive transitions. Thermodynamic information related to low-energy excitations of itinerant electrons gives clue for understanding the mechanism of them [6]. Relaxors: The relaxor is characterized by a large, broad and frequency-dependent dielectric constant peak extending a wide temperature range. The giant electromechanical response in ferroelectric relaxors is of great importance for a number of ultrasonic and medical applications as well as in telecommunications. Papers concerning calorimetry of other functional materials will be published in the forthcoming Part III. We would like to thank Prof. Yann Garcia, the Editor-in-Chief of Current Inorganic Chemistry, who invited us to edit a thematic issue concerning calorimety of inorganic materials. We would like to acknowledge all the authors who accepted our invitation to contribute to this thematic issue, as well as the reviewers who invested their valuable time to ensure the high scientific quality of all contributions.
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